/Engine/Source/Runtime/MovieScene/Public/MovieSceneKeyStructHelper.h
Attempt to find a single key handle that exists on the specified channel
(Optional) A key handle and time pair for the first valid key handle found
template<typename ChannelType> static [TOptional](API\Runtime\Core\IO\TOptional)< [TTuple](API\Runtime\Core\Misc\TTuple)< [FKeyHandle](API\Runtime\Engine\Curves\FKeyHandle), [FFrameNumber](API\Runtime\Core\Misc\FFrameNumber) > > FindFirstKey ( ChannelType * InChannel, [TArrayView](API\Runtime\Core\Containers\TArrayView)< const [FKeyHandle](API\Runtime\Engine\Curves\FKeyHandle) > AllKeyHandles )